In model tests in the aspect of the geotechnical engineering, the studies on the internal transformation law and mechanism of soil bodies are of great significance on the research of the problem inherence of the geotechnical engineering. Particularly, the area of perennial frozen soil, seasonal frozen soil and temporary frozen soil regions on earth approximately accounts for 50% of the land area, wherein the distribution area of perennial frozen soil is 35,000,000 km2, approximately accounting for 20% of the land area. Frozen soil is a soil body extremely sensitive to the temperature, along with the rise of the temperature, its strength obviously reduces, and the strength after the soil body thaws reduces by a geometry order-of-magnitude relative to that while in freezing. The results of related studies show that, hilly areas of the abdominal zones of perennial frozen soil regions in Qinghai-Tibet Plateau and the like are all possible to form thaw slumping on the sloping land greater than 3° in its thawing process. When the surface layer frozen soil thaws due to the rise of the atmospheric temperature, under the condition of high ice content, a sliding soil body appears as a mixture of hard rock blocks and liquid slurry, and is easy to generate a sliding plane approximately parallel with the slope face. For example, in a region between WUdaoliang and Tuotuohe near the milestone of the K3035 mileage segment of the Qinghai-Tibet highway, with the overall slope of about 7°, a topical thaw-slumping phenomenon with the longitudinal direction of 95 m and the maximum width of 72 m occurs. Hence, it is important to develop the studies on the thaw-slumping characteristics and mechanism of low-angle side slopes.
The document “Study on Model Experiment of Thaw Slumping in Permafrost Region of Qinghai-Tibet Plateau” (Jin Dewu, et al. Engineering Investigation, 2006, 9: 1-6) designed a physical model (compressed at a scale of 1:10) similar to the geometry and slope structure of the thaw-slumping body of the K3035 mileage segment of the Qinghai-Tibet highway, and the testing process was divided into several links of ice box processing and ice layer fabrication, soil sample rolling and preparation; correction and calibration of monitoring instruments, fabrication of a slope scale model in a model box and instrument embodiment; and a special ice layer was used in the test process for the temperature control, the temperature was set at −1° C., the other one was used for controlling the temperature of the soil body, total four freezing-thawing periodic cycles were completed, and based on pre-embedded common temperature probes, displacement sensors and extensimeters, the displacement field and the temperature field of the side slop could be measured. However, conventional soil body deformation measurement method is to embed a series of sensors inside the soil body, and obtain the displacements of some discrete points, the sensors are easily subjected to the effect due to the disturbance of the external environment, the measurement result often are not accurate, and the whole displacement field in continuous deformation inside the soil body can not be presented as well. Modern digital image technologies are only limited to measure the macroscopic or boundary deformation of the soil body as well, and can not realize the visualization of the internal deformation of the soil body; and although X-ray, γ-ray, computer assisted tomographic scanning (CAT scanning) and magnetic resonance imaging technology (MRI) can be used for measuring the continuous deformation inside the soil body, and expensive expenses limit wide application of these technologies.
Controlled blasting is a blasting technique, which controls public hazards of frying objects, earthquake, air shock wave, fume, noise and so on generated due to the explosion of an object to be blasted by explosive by certain technical means, and has wide application in the engineering construction, for example, directional blasting, presplitting blasting, smooth surface blasting, rock plug blasting, millisecond controlled blasting; demolition blasting, static blasting, casting-filling blasting, weakly loose blasting, combustion agent blasting and the like. The directional blasting is a blasting technique, which utilizes the explosion action of explosive, to throw earth and stone of a certain region to a specified region and approximately stack into a required shape, is mainly used for repairing dams (water dams or tailing dams), building roads (road embankments and roadbeds), and leveling land (industrial lands and farmland construction), and is particularly suitable for work points of labor shortage, inconvenient transportation and no construction yard.
Document 1 “Study on Frozen Soil Blasting Crater and Model Test Of Frozen Soil Blastability” (Ma Qinyong. Journal of China Coal Society, 1997, 22(3): 288-293) disclosed a program for the blasting crater model tests of frozen clay and sand soil at different temperatures; document 2 “Preliminary Study on Blasting Parameters for Shaft Excavation in Frozen Soil” (Zong Qi, Yang Lujun, Engineering blasting, 1999, 5(2): 25-29), and document 3 “Study of Smooth Blasting in Frozen Soil of the Shaft by Simulation” (Jiang Yusong, Journal of Huainan Institute of Technology) (2001, 21(4): 31-34) disclosed a program for cutting blasting and smooth blasting model tests of frozen sand soil; and Document 4 “A Study on Blasting Tests and Methods for Permafrost and Artificially Frozen Soils” (Ma Qinyong, Journal of Civil Engineering, 2004, 37(9): 75-78) comprehensively introduced the research developments and achievements of blasting craters, cutting blasting and smooth blasting tests of frozen soil. These model test programs are all based on conventional test means, and are incapable of effectively acquiring specific fracture morphologies of frozen soil after the blasting tests. However, conventional soil body deformation measurement method is to embed a series of sensors inside the soil body, and obtain the displacements of some discrete points, the sensors are easily subjected to the effect due to the disturbance of the external environment, the measurement result often are not accurate, and the whole displacement field in continuous deformation inside the soil body can not be presented as well. Modern digital image technologies are only limited to measure the macroscopic or boundary deformation of the soil body as well, and can not realize the visualization of the internal deformation of the soil body; and although X-ray, γ-ray, computer assisted tomographic scanning (CAT scanning) and magnetic resonance imaging technology (MRI) can be used for measuring the continuous deformation inside the soil body, and expensive expenses limit wide application of these technologies.
Artificial synthesis of transparent soil in combination with optical observation and image processing techniques is utilized to realize the visualization of the internal deformation of the soil body, with low expense, and simple operation, and can be widely applied in model tests in the aspect of the geotechnical engineering, to study the internal law and mechanism of the soil body, which is of great significance on the research of the problem inherence of the geotechnical engineering. Its precondition is to obtain an artificially synthesized transparent soil with high transparency, and the properties similar to natural soil body. At present, different materials were adopted to prepare transparent soil, and some achievements were obtained. However, existing technical data show that, solid particles for preparing transparent soil mainly adopt quartz materials, with the refractive index themselves of the solid particles between 1.44-1.46, and adopt borosilicate glass materials, with the refractive index themselves of the solid particles between 1.46-1.48, which is far higher than the refractive index of water of 1.33 and that of ice of 1.31. Hence, the utilization of existing solid particles for preparing transparent soil is incapable of preparing a saturated transparent frozen soil sample.
The fluorine-containing polymer is Teflon AF 1600 produced by American DuPont Company (i.e. poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]), with the refractive index of 1.31, and the density of 2.1-2.3 g/cm3; and it has the characteristics of high temperature resistance, low temperature resistance, chemical corrosion resistance, no viscosity, no toxicity, no pollution, high transparency and low refractive index, and also has the characteristics of gas permeability structure, hydrophobicity and chemical inertness, and has good similarity with the properties of natural soil body. Teflon AF 1600 (i.e. poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]) can be dissolved in fluorine solvents, and can be formed into a film or formed by fusion compression; and at present, it is mainly used in coating and impregnation or made into fibers, and the prepared liquid core also has application in various fields of absorption, fluorescence, Raman spectral analysis, gas sensors and the like. The fluorine-containing polymer has high transparency, and the refractive index the same as ice, thus can be used as a transparent solid material in the preparation of transparent frozen soil.